PRECAUTION DURING EXCAVATION:
There are following precaution is to be taken during excavation-
·
The width of trench is kept 30
to 45 cm more than the diameter of the pipe because the pipe is laid down in
the trench easily.
·
The depth of trench from ground
level is kept 90cm to 1m because the pipes not breakdown where pressure or load
applied on the pipe.
·
The excavated soil is kept 1.5
mt away from corner of trench because it will not come in trench.
·
Plank shuttering used in soft
soil if necessary.
·
The disturbance in traffic will
be minimum and the traffic of one direction is almost freely.
·
At the time of excavation of
trench it is necessary that no damage of electric poles, trees which is
available nearby trench.
·
In big residential areas the
pipe line is kept open about 30 mt, and in less residential areas the pipe line
is kept open about 100 mt.
·
if the distance is above this
range then danger of fall any person or animal is create. The arrangement of material care is very
important which are used in excavation of trench.
PRECAUTION TAKEN FOR TRAFFIC CONTROL:
Following precautions can be taken for traffic control during excavation –
·
The work shall be carried in
such a manner that it causes the least interruption to traffic.
·
Provide a safe alternate route
for traffic.
·
Where it is necessary for
traffic to cross open trenches, suitable bridges shall be provided.
·
Suitable signs indicating that
a street is closed shall be placed.
PREPARATION OF BEDDING:
·
Before laying of pipe lines the
base of trench is kept in accurate slope with the help of boing rod.
·
Pipe is not laying directly in
the trench because if the clay of trench is settle down then there is chance to
break the pipe.
·
So, on the base of trench first
of all laying brick ballast and pounding the brick ballast accurately.
·
Depth of trench is kept
approximately 15 to 20 cm more in length of 1 mt where the joint of pipe is
available because the joint of pipe is done easily.
·
If the soil is soft then a
layer of cement concrete is provided on the brick ballast.
HANDLING OF PIPES –
·
All pipes shall be lifted by
means of reinforced canvas slings.
·
The pipes should be lifted by
means o hooks to the ends of pipe.
·
All the open ends of the pipes
shall be closed by means of end caps or polythene sheets before delivery to
site.
·
After delivery to the site,
these , end caps should not be removed until the pipes are ready to the laid
·
All open ends of pipes in the
trenches shall remain covered to prevent the entry of any dirt, mud, stone.
·
The cover should be the water
tight to prevent the entry of dirty water.
TESTING OF PIPE LINES:
After completion of the work the pipeline should be tested to detect the leakage if any in the pipeline
(1) Pressure test-
·
A section of the pipeline
should be filled with water.
·
And pressure should be applied
by pump.
·
The pressure is noted on the
pressure gauge.
·
If the pressure on the gauge
falls gradually, then it indicates the leakage in that section of pipeline.
(2) Leakage test by Empirical formula:
The allowable leakage is given by the relation
L = ND√P / 3.3
L = allowable leakage
N = number of joints
D = diameter of pipes
P = applied pressure
If the actual leakage is more than the allowable leakage then the leakage point should be detected and rectified accordingly